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sanyo plv 30 screen burn!!!!

Discussion in 'Projectors, Screens & Video Processors' started by True Romance, Feb 7, 2005.

  1. True Romance

    True Romance
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    i have a plv 30 pj which has been great for over 3 years. i only use it for flims which i show in widescreen, but the other day a put on a full screen film and was alarmed to see light bands across the top and bottom of the screen, it looks like screen burn where the pj has been projecting black bars from widescreen films! has anyone come across this problem? many thanks.
     
  2. PJTX100

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    You know, the other night while looking at the Pioneer logo bobbing about the screen to prevent screen burn I thought "I wonder why the black bars don't cause issues?"

    I'll be interested to see the replies. My gut feel it that it's healthy to play around with the AR stretch or play a 16:9 DVD on a regular basis to stop that part of the screen getting lazy?! But I'd be relieved to be told this was rubbish. :)

    So far, until your post, I've seen no comment on this at all...PJ
     
  3. drummerjohn

    drummerjohn
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    Its a known issue with LCD projectors. Because the bars in the film are black the LCD panels are obviously black. Black sucks the heat into the LCD panel thus causing heat damage to them.
     
  4. theritz

    theritz
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    I've read about image persistance on LCD monitors, usually evidenced by "ghosting" of bright elements of a previous image (like the "Start" button on a desktop, or a bright component of a Desktop background image that's been left displaying for very extended periods). This problem can be rectified, although it sometimes is permanent - afaik it depends on the LCD panels themselves and the degree of strength of the ghosting, a bit of a luck of the draw issue.

    As for it being a known issue, I can't recall having come across reports of it on LCD projectors - after 2000 hrs of overwhelmingly 2.35:1 viewing myself, there's no evidence of a ghost of the black bars when displaying a Windows desktop or a 1.85:1 movie. As for the "black sucks the heat into the LCD panel" comment - I'd be inclined to think that the differential in the heat on the surface of the LCD panel between the image displayed and the grey bars would be unlikely to be sufficient to cause damage only to the "black bars" portion of the panel. Not disagreeing for the sake of being awkward, just don't find the explanation convincing.

    Because you describe the "black bars" area as lighter than the rest, I doubt that it's ghosting or persistance - if it were the case. I would expect the "black bars" areas to be darker, and the 2.35:1 area to be lighter, and all the more so if it were (albeit unlikely imho,) LCD panel damage.

    Bit of a puzzle, really..... You could try displaying a full white field ( use Avia if you have it, alternatively hook up a PC, draw an all-white image in MSPaint the same size in pixels as the native size of the LCD panels, set MSPaint to View Image so that all that's displayed is an all white screen and leave it on for a couple of hours - this might remedy the problem if it is image persistance.

    Hope you get a solution for this one......

    Sean G.
     
  5. RTFM

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    If you think about how LCD technology works, ie. polarised light passing through the LCD panels which consist of millions of crytsals in suspension either in a random pattern or all lined up (when they too become a polarised medium), I can't see how screen burn could occurr.
    Could be worth running the thread on the AVS Forum and asking some of the boffins there, and believe me some of the guys are very clued up.
    Not to say there aren't people on this forum of a similar calibre. :)

    Jeff :rtfm:
     
  6. True Romance

    True Romance
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    thanks for the advice, just to let you know i've emailed sanyo twice with no response, so no luck there, and just checked lamp timer it's only done 260hrs. i was thinking of getting the sanyo plv-z3 but with no response from customer services i think i'll look at the infocus 4805. as anyone compared the two?

    once again many thanks for your help.
     
  7. Kahless725

    Kahless725
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    Ive heard of this on Plasmas but never on an LCD? Weird. Anyone else at all experienced this with LCD technology?
     
  8. Comer

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    I don't think it could be screenburn after only 260 hours!!
     
  9. miremare

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    I have a similar problem too.
    I have watched a lot of full screen 4:3 movies and a lot of 16:9 movies.

    With my sanyo, at first there was no problem.
    about 1 month ago i noticed a bar at the top of a screen when watching a 4:3 movie.

    recently, the bar is also at the bottom.

    Its not completely distinct, but just enough for you to know there is something up.

    On some films its not noticable, on others its very.

    It seems to be affecting certain colours more than others.

    I have a sDVDO iscan Pro by silicon image.
    I dont have rgb just 2 X comosite inputs.
    therefore i cant experiment with other colours.

    Im just interested to know if this is something to do do with the bulb, or if the lcd panels have been affected.

    I use my projector celling mounted.

    any help is appreciated.

    oh yes bulb life is about half way through
     
  10. Mark_a

    Mark_a
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    I did read somewhere that there was a cure for screen burn by running your device, be it plasma or whatever, with a completely white screen for a couple of hours, or if really bad, over night. This has the effect of bringing all the picture elements into the same state.

    Now, never having had to do this myself, I can't vouch for it, but it did seem something reasonable to at least try if you're having problems.

    Don't blame me if it makes things worse though.

    Regards

    Mark
     
  11. Nick_UK

    Nick_UK
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    You are talking about TV's. Projectors are a different matter entirely. There's a lot of heat from a pj bulb, and I can accept the "cooked crystal" theory.
     
  12. theritz

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    I still doubt that this could be persistence.....


    S
     
  13. Daftboy

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    Sounds like wear in the optics or LCD panels. Look at some websites where they have done long life tests on LCD projectors. After about 4,000 hours they blob in the middle and spread out. Normally this can be a cheap repair unless it is damage to the panels.
    Unfortunatley, diffect LCD's go at different times. From what Iread, it's very dependant on LCD panel manufacturers, unit brightness and quality of optics.
    Best of luck and hopefully they will sort it out under warranty!
     

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